Dissociable Aspects of Mental Workload : Examinations of the P300 ERP Component and Performance Assessments
C. L. Baldwin & J. T. Coyne
Advanced technologies have enabled the choice of either visual or auditory formats for avionics and surface transportation displays. Methods of assessing the mental workload imposed by displays of different formats are critical to their successful implementation. Towards this end a series of investigations were conducted with the following aims: 1) developing analogous auditory and visual versions of a secondary task that could be used to compare display modalities; and 2) to compare the sensitivity of neurophysiological, behavioral and subjective indices of workload. Experiments 1 and 2 confirmed that analogous auditory and visual secondary oddball discrimination tasks were of equivalent difficulty as indicated by P300 amplitude, RT, accuracy and subjective ratings of workload. Experiments 1-3 revealed that RT and accuracy for target detections were generally more sensitive to changes in primary task difficulty than P300 responses and subjective ratings. However, Experiment 3 indicated that P300 amplitude was sensitive to increased perceptual demands (resulting from driving in heavy fag versus clear visibility} not revealed by changes in either behavioral or subjective indices. Together the results of the current investigations indicate that a battery of assessment techniques will provide the most sensitive assessment of workload in complex environments.

Key words: mental workload assessment, display modality, transportation, neurophysiological measures, adaptive automation